General Mills Inc (GIS.N) on Tuesday issued a voluntary recall of about 10 million pounds of flour, saying it was working with health officials to investigate an outbreak of E. coli that had sickened 38 people in 20 U.S. states. The bacteria strain behind the outbreak has not been found in any of General Mills Gold Medal, Wondra and Signature Kitchens flour or their manufacturing plant, the company said. Consumers have not contacted it directly to report any illnesses, the Minneapolis-based company added. "Out of an abundance of caution, a voluntary recall is being made," General Mills said.